#include "apue.h"
#include<errno.h>
#include<limits.h>

#ifdef PATH_MAX
static int pathmax = PATH_MAX;
#else
static int pathmax = 0;
#endif

#define SUSV3 200112L

static long posix_version = 0;

#define PATH_MAX_GUESS 1024

char *path_alloc(int *sizep)
{
	char *ptr;
	int size;

	if(posix_version == 0)
		posix_version = sysconf(_SC_VERSION);

	if(pathmax == 0) {
		errno = 0;
		if((pathmax = pathconf("/", _PC_PATH_MAX)) < 0) {
			if(errno == 0)
				pathmax = PATH_MAX_GUESS;
			else
				err_sys("pathconf error for _PC_PATH_MAX");
		} else
			pathmax++;
	}

	if(posix_version < SUSV3)
		size = pathmax + 1;
	else
		size = pathmax;

	if((ptr = malloc(size)) == NULL)
		err_sys("malloc error for pathname");

	if(sizep != NULL)\
		*sizep = size;

	return (ptr);
}
